The Emerging Weak Antilocalization Effect in Semimetal Ta$_{0.7}$Nb$_{0.3}$Sb$_2$ Single Crystal

TL;DR

This study reports the observation of weak antilocalization in high-quality Ta0.7Nb0.3Sb2 semimetal single crystals, revealing unique magnetic and transport properties that could inspire further theoretical and practical research.

Contribution

It is the first to demonstrate WAL effect in Ta0.7Nb0.3Sb2 single crystals and explores their magnetic-field-induced symmetry changes and high carrier mobility.

Findings

WAL effect observed below 50°C in Ta0.7Nb0.3Sb2 crystals

High carrier mobility (>1000 cm²V⁻¹s⁻¹) across 2-300°C

Magnetic-field-induced symmetry change in angular magnetoresistance

Abstract

Weak antilocalization (WAL) effect is commonly observed in 2D systems, or 3D topological insulators, topological semimetal systems. Here we report the clear sign of WAL effect in high quality Ta$_{0.7}$Nb$_{0.3}$Sb$_2$ single crystals, in below 50$^\circ$ K region. The chemical vapor transport method was employed to grow the single crystal samples, the high crystallization quality and uniform element distribution are verified by X-ray diffractions and electron microscopy techniques. Employing the Hall effect and two-band model fitting, the high carrier mobility (> 1000 cm$^2$V$^{-1}$s$^{-1}$ in 2 to 300$^\circ$ K region) and off-compensation electron/hole ratio are obtained. Due to the different angular dependence of WAL effect and the fermiology of Ta$_{0.7}$Nb$_{0.3}$Sb$_2$ single crystal, interesting magnetic-field-induced symmetry change is observed in angular magnetoresistance. These interesting transport properties will lead to more theoretical and applicational exploration in Ta$_{0.7}$Nb$_{0.3}$Sb$_2$ and related semimetal materials.